(1) Field of the Invention
The present invention relates to a smart antenna and, more particularly, to a smart antenna including a receiving element to be held above a television receiver.
(2) Description of Related Art
When a television viewer adjusts the direction of an antenna by a known antenna adjusting method, the television viewer adjusts the direction of an antenna making reference to an image displayed on the screen of a television receiver to an optimum receiving direction for receiving broadcast television signals. However, this known antenna adjusting method is very troublesome. Some antenna system includes a receiving condition indicator, and an antenna whose direction can be manually adjusted making reference to a receiving condition indicated by the receiving condition indicator. Another known antenna system includes an antenna whose direction can be automatically adjusted in response to a request made by the television viewer.
A previously proposed antenna system includes an antenna whose directivity can be automatically changed every time a desired channel is selected. Generally, such an antenna is called “smart antenna.” Referring to FIG. 7 showing a known smart antenna 1 in a perspective view, the smart antenna 1 includes an antenna unit 2 provided with a receiving element, a housing 3 holding the antenna unit 2 therein, a support rod holding the housing 3 at a predetermined height and fastened to a television receiving system 6, and a wiring 5 electrically connecting the antenna unit 2 to the television receiving system 6. The television receiving system 6 controls the smart antenna 1 through the wiring 5 on the basis of predetermined standards to change the receiving directivity of the smart antenna 1.
When the smart antenna 1 is connected to the television receiver 6, the receiving element 2 needs to be set substantially horizontally when the television receiver 6 is installed on a horizontal surface at a predetermined distance from the television receiver 6 to ensure that the antenna element exercise a high receiving sensitivity. Generally, a room antenna has an antenna element, namely, a receiving element for receiving broadcast television signals, capable of being extended to raise its receiving sensitivity. In the smart antenna, the receiving element is extended horizontally so that the directivity can be changed. Therefore, the housing 3 holding the receiving element therein needs to be set at a predetermined distance from the television receiver 6.
The smart antenna 1 has the following problems. The wiring 5 electrically connecting the antenna unit 2 to the television receiver 6 spoils the aesthetic appearance and is broken often. As shown in FIG. 7, the wiring 5 is extended from the housing 3 set above the television receiver 6 and is connected to the television receiver 6 set below the housing 3. Therefore, the wiring 5 is conspicuous and spoils the aesthetic appearance of the television receiver 6. Moreover, the wiring 5 extended from the housing 3 breaks if the wiring 5 is caught by an obstacle.
A wiring laying method is disclosed previously in, for example, JP-U H6-9210. In a CS/BS antenna for receiving CS/BS broadcast signals, a cable connected to a BS converter and a driver is extended through a support arm supporting a parabola unit. Thus the appearance of the CS/BS antenna can be improved by concealing the wiring from view.
Another wiring laying method disclosed in, for example, JP-A H7-154122 extends a coaxial cable connecting an antenna and a satellite through a round waveguide serving also as a support pipe, and connects an end part of the coaxial cable extending outside from the lower end of the waveguide to the satellite.
The following problems arise when the inventions disclosed in JP-U H6-9210 and JP-A H7-154122 are applied to a smart antenna. As mentioned above, the receiving element of a smart antenna is set above a television receiver to receive television signals in a high sensitivity. Therefore a wiring is extended down from a position above the television receiver. The smart antenna is highly sensitive to signals owing to its own properties and, in some housings, the sensitivity of the smart antenna deteriorates when a conductive matter is brought close to the antenna unit or the wiring. Thus, the ordinary wiring method, in some housings, deteriorates the sensitivity of a smart antenna.